Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation [Abstract]
Number of Shares Available for Grant, Beginning balance	653,136	818,002	38,055
Number of Shares Available for Grant, Options authorized		814,184	837,000
Number of Shares Available for Grant, Assumed as part of the Merger	2,707,144
Number of Shares Available for Grant, Options granted	(1,914,142)	(1,124,430)	(210,452)
Number of Shares Available for Grant, Options forfeited or cancelled	293,483	145,380	153,399
Number of Shares Available for Grant, Ending balance	1,739,621	653,136	818,002	38,055
Number of Shares Underlying Outstanding Options, Beginning balance	1,860,646	896,539	963,435
Number of Shares Underlying Outstanding Options, Assumed as part of the Merger	81,370
Number of Shares Underlying Outstanding Options, Options granted	2,276,645	1,124,430	210,452
Number of Shares Underlying Outstanding Options, Options exercised	(210,752)	(14,791)	(123,949)
Number of Shares Underlying Outstanding Options, Options forfeited or cancelled	(300,964)	(145,532)	(153,399)
Number of Shares Underlying Outstanding Options, Ending balance	3,706,945	1,860,646	896,539	963,435
Number of Shares Underlying Outstanding Options, Shares exercisable	1,219,904
Number of Shares Underlying Outstanding Options, Vested and expected to vest	3,706,945
Weighted-Average Exercise Price, Outstanding beginning	$ 4.05	$ 2.04	$ 2.02
Weighted-Average Exercise Price, Assumed as part the Merger	8.39
Weighted-Average Exercise Price, Options granted	15.14	5.39	2.26
Weighted-Average Exercise Price, Options exercised	2.18	2.12	1.92
Weighted-Average Exercise Price, Options forfeited or cancelled	6.04	2.17	2.25
Weighted-Average Exercise Price, Outstanding ending	10.90	$ 4.05	$ 2.04	$ 2.02
Weighted-Average Exercise Price, Shares exercisable	4.64
Weighted-Average Exercise Price, Vested and expected to vest	$ 10.90
Weighted-Average Remaining Contract Term, Outstanding	7 years 11 months 23 days	8 years 6 months 10 days	8 years 6 months 25 days	9 years 3 months 7 days
Weighted-Average Remaining Contract Term, Shares exercisable	5 years 1 month 9 days
Weighted-Average Remaining Contract Term, Vested and expected to vest	7 years 11 months 23 days
Aggregate Intrinsic Value, Outstanding	$ 15,126	$ 5,812	$ 2,436	$ 4,977
Aggregate Intrinsic Value, Shares exercisable	11,563
Aggregate Intrinsic Value, Vested and expected to vest	$ 15,126